In the related art, an image forming apparatus such as a digital multi-functional peripheral performs printing by putting both sides of the original document together on a single side of one sheet (both side disposition copying). As an example of the both side disposition copying, there is a function referred to as card copying. In card copying, both sides of the original document in a card shape such as an ID card are copied on a single side of one sheet. In card copying in the related art, there are two methods as described below. In the first method, an image including the front surface of the original document is copied on the upper half portion of a sheet, and an image including the rear surface of the original document is copied on the lower half portion of the sheet. In the second method, an image on the front surface of the original document which is read in a size designated by a user is disposed at a center of the upper half portion of a sheet, an image on the rear surface of the original document is disposed at the center of the lower half portion of the sheet, and the images are printed on the sheet. However, in the first method, a user should set the front surface and the rear surface of the original document, respectively, by assuming a half region of the sheet. In addition, in the second method, there is a problem in that a user needs to designate a size of the original document accurately.